Functions
2.22 Overvoltage Protection (ANSI 59)
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
178
2.22 Overvoltage Protection (ANSI 59)
Overvoltage protection serves to protect the electrical machine and connected electrical plant components
from the effects of inadmissible voltage increases. Overvoltages can be caused by incorrect manual operation
of the excitation system, faulty operation of the automatic voltage regulator, (full) load shedding of a generator,
separation of the generator from the system or during island operation.
2.22.1 Functional Description
Mode of Operation
The overvoltage protection provides the option to either select whether the phase-to-phase voltages or the
phase-to-ground voltages will be monitored. In case of a high overvoltage, tripping switchoff is performed with
a short-time delay, whereas in case of less severe overvoltages, the switchoff is performed with a longer time
delay. Voltage thresholds and time delays can be set individually for both elements.
Each stage can be blocked individually, both stages together, via binary input(s).
The following figure shows the logic diagram for the overvoltage protection function.
Figure 2-74 Logic Diagram of the Overvoltage Protection
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